The main objective is to determine compositional and structural details of the inorganic phase in teeth and bones. Infrared and Raman spectroscopy, x-ray diffraction and chemical methods are employed in these studies. A better understanding of the compositional and structural details of the apatite mineral phase in teeth and bones has been made possible by studies on its synthetic analogs. Consequently, methods are devised for the preparation of synthetic calcium apatites having controlled physical properties (crystal size and shape and crystal perfection) and chemical constituents (hydroxide, fluoride, chloride, carbonate, water, acid phosphate and other ions). Isotopically enriched apatite analogs are also prepared to facilitate spectral assignments. The vibrational spectra of these apatites and related compounds are assigned using factor group symmetry methods. The spectroscopic band assignments and supplemental data (temperature dependence and polarization of bands) are then utilized to establish compositional and structural details of the apatites in question, which include: the type and geometry of constituent ions; the site and number of sites occupied by the ions; orientation of ions; chemical bonding and interactions of ions; and semi-quantitative estimations of constituents present. The results of these controlled apatite systems are then related to the inorganic phase in calcified tissues. The infrared and Raman spectroscopic and x-ray diffraction methods are also utilized in dental materials research to determine and monitor reactions during syntheses of various inorganic and organic compounds used for composites, coupling agents, cements and other dental materials.